1. Field of the Invention
This invention relates to selectively pyrolyzed, electrically conductive, thermoplastic web materials. In preferred forms, composites including the web materials of this invention exhibit high temperature stability and increased electrical conductivity over the surface and through the thickness of the composite. Preferred composites find use in a variety of applications including such things as image transfer belts in thermal printers and copying machines.
2. Discussion of the Prior Art
Flexible, electrically-conductive sheet materials of a variety of constructions have been previously disclosed for use in copying or image recording devices. U.S. Pat. Nos. 4,248,952 and 4,248,521 disclose such sheet materials wherein the center layer of the construction is made from electrically conductive material. U.S. Pat. Nos. 4,015,027 and 3,993,825 disclose toner transfer belts for use in electrostatic copying devices wherein the belts have a metal center layer.
Record storage media have been disclosed wherein holes in a plate of dielectric material are said to provide information by whether or not the walls of the holes have been carbonized by an electric discharge. U.S. Pat. No. 3,641,318 discloses such a plate having holes in predetermined, informational patterns. Although all of the holes do not have carbonized walls, there is disclosure that the holes can be made by electric discharge.
Electrical resistors are disclosed as made from polyimides charred by a laser beam in U.S. Pat. No. 4,286,250.
Electric discharge has been taught for perforating or bonding dielectric sheet materials in U.S. Pat. Nos. 4,278,871; 4,025,752; 3,424,895; 3,385,951; 2,678,373; and 3,760,153.